The present invention generally relates to a medical image diagnostic system and more particularly to a medical picture diagnosis system provided with an image processing device, an image display device for displaying an image formed by the image processing device, and a photographing device for photographing and recording the images thus displayed in a desired format.
Recently, in the field of medical diagnostic systems, there has been known a system including a device for processing an image signal transferred from a computer tomography apparatus (X-ray CT) or a nuclear magnetic resonance computer tomography apparatus (NMRCT) using a computer to thereby obtain a clear image of a portion of the patient's body. The system further includes a device responsive to the image-processing device for displaying the image on a display device, for example, a cathode-ray tube (CRT) display device, and a device for photographing the displayed image.
For example, a CT system using X-rays has been put to widespread use because such a system provides superior image quality since slight differences in X-ray absorption coefficients can be readily recognized. Further, besides such systems using X-rays, there have been known an emission CT device using radioisotopes in which the distribution of radioisotopes absorbed in a patient's body is scanned by a detector so as to reconstruct a tomographic image of the body, a positron CT system wherein X-ray beams opposed to each other by 180 degrees are generated when protons are combined with electrons and extinguished, and an NMRCT system which utilizes nuclear magnetic resonance (which has the advantage of no radiation hazard) and which is particularly suitable for detecting the state of fluids in the patient's body.
Moreover, there has been known a camera system, referred to as a medical imaging camera, in which an image displayed on a display device such as a CRT can be photographed in a desired format. This camera system is suitable for recording and preserving images displayed on a display device in accordance with a signal transferred from a diagnostic system. In this system, the exposed film is developed by an automatic developer.
Of these two types of systems, one is a medical diagnostic system for displaying a preferred diagnostic image of an affected part of a patient's body, and the other is a system for recording the displayed image. Recently, attempts have been made to combine these two types of systems into one so as to obtain a complete medical image diagnostic system. Such a medical image diagnostic system can be easily constructed merely by connecting the output signal of a diagnostic image detection device to a video input terminal of an image display device through an appropriate image processing device and a video signal converting circuit.
In such a medical image diagnostic system, there occurs no difficulty in the case where the diagnostic image detection device, the image display device, and the displayed image photographing device are connected with each other using ordinary high-frequency cables if all these devices are arranged integrally with each other or disposed close to each other. However, in the case where the image display device and the displayed image photographing device are located at some distance from one another, problems in signal transmission often occur.
Further, there is a need for the image density to be made greater, for example, by increasing the number of scanning lines from about 500 to about 1000. In such a case, a sufficient bandwidth cannot be obtained using ordinary high-frequency cables. Moreover, the phase characteristics of the image signal are such that, in the case where the video converting circuit, the image display device, and the displayed image photographing device are connected to each other through ordinary high-frequency cables of a length of several tens of meters or more, the image signal transferred from the video converting circuit cannot be correctly displayed on the display device, and in some cases, the displayed image cannot be clearly reproduced by the displayed image photographing device.